6-Hydroxy-L-DOPA is the 6-hydroxy derivative of the amino acid L-DOPA with neurotoxic properties. Exogenously administered 6-Hydroxy-L-DOPA is biotransformed by an amino acid decarboxylase to the highly potent and catecholamine-selective neurotoxin, 6-Hydroxydopamine.
3-O-methyl-L-DOPA is a metabolite of L-DOPA , produced by the activity of catechol O-methyltransferase. 3-O-methyl-L-DOPA may have effects of its own or it may compete with the actions of L-DOPA.